This is the brainchild of Joanna Monteith, founder of Consult. As a consultant she was always customising MYOB and Quickbook templates and thought it would be great to share these with other consultants and make available a catalogue for new clients to choose from. When Xero came along with a nicer standard design she put the idea on the backburner thinking it would no longer be needed. However, it proved to be the opposite with all the "bigger" programs having the ability to import docx files and businesses/consultants wanting to push the software to it's limits.
Some of the smaller web based software has inbuilt templates, but these prove to be restrictive and the trend is towards being able to customise.